Accession Number:

ADA080384

Title:

Barriers to the Migration of Interphase Boundaries, Particularly in Steel.

Descriptive Note:

Rept. no. 17 (Final) 15 Oct 76-14 Sep 79,

Corporate Author:

MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF METALLURGICAL ENGINEERING

Report Date:

1979-12-20

Pagination or Media Count:

113.0

Abstract:

The growth kinetics of proeutectoid ferrite, in the form of grain boundary allotriomorphs, were measured vs. reaction temperature in Fe-C-X alloys where X was Si, Mn, Cr and Ni. Comparison of measured growth kinetics with those calculated often shows poor agreement with the local equilibrium model order of magnitude agreement was obtained with both the pileup and the paraequilibrium models. A limiting alloying element penetration calculation, however, showed that only the paraequilibrium model is basically consistent with the experimental data. TEM studies showed that measured growth kinetics somewhat slower than those predicted by the paraequilibrium model are not due to carbide precipitation at austeniteferrite boundaries. Such slower growth kinetics appear to be best explained by a solute drag-like effect. Carbide precipitation at austeniteferrite boundaries in Fe-C-X alloys was shown to increase growth kinetics when X is Si, Ni and V. Incomplete transformation in Fe-C-Mo alloys was demonstrated to occur only when critical proportions of C and Mo are exceeded. Thermodynamics of the proeutectoid ferrite reaction in Fe-C alloys were reassessed using recent theory and thermodynamic data. Structural ledges were observed to occur reproducibly on planar facets formed during the beta yield alpha sub m Cu-Zn massive transformation. The misfit dislocation structure of the lamellar interfaces in the CoAl-CoAl eutectic was observed to be significantly affected by the presence of LRO in the CoAl phase. Author

Subject Categories:

  • Metallurgy and Metallography
  • Crystallography

Distribution Statement:

APPROVED FOR PUBLIC RELEASE